(P-TS-80) Post-natal Laboratory and Clinical Characteristics of Infants Born to Alloimmunized Mothers. Data from a Canadian Provincial Alloimmunization Program (PRAMS).

Hemolytic disease of the fetus and newborn (HDFN) due to red cell alloimmunization predisposes neonates to  fetal hydrops, neonatal kernicterus and anemia. Prenatal management of the expectant patient to reduce the risk of HDFN complications is well-established, with guidelines published by several national and international organizations. However, limited evidence exists regarding the postnatal course and follow-up of infants with HDFN, leading to a scarcity of management recommendations.

The PRAMS (Prevention of Alloimmunization in Mothers of Saskatchewan) Program includes a provincial multidisciplinary team focused on prevention of D-alloimmunization, surveillance of alloimmunized expectant patients, and follow up of neonates born to alloimmunized individuals. This retrospective cohort summarizes the postnatal course of infants born to alloimmunized individuals since the inception of PRAMS program.

Study

Design/Methods:

Cases were defined as neonates born to alloimmunized individuals who had hemolysis with a positive cognate RBC antigen or who had received RBC intrauterine transfusions (IUT). A chart review of these cases was completed from February 2020 to December 2023.Provincial Lab Information System was queried for maternal antibody type, titers (performed in gel with titer ≥64 or anti-Kell considered critical) and neonatal transfusion testing data (ABO, Rh, DAT, red cell antigen phenotyping in tube).Following variables were collected on the cases: serial hemoglobin levels, hemolytic markers, interventions for anemia management and time to resolution.

Descriptive continuous variables were represented as means with standard deviations whereas categorical variables were reported as proportions. The Chi-square test was used to determine association of antibody type with HDFN severity. Data was collected in Redcap and analysis conducted in SAS version 9.4.

Results/Findings:

A total of 424/55,464 (0.8%) expectant patients had clinically significant antibodies with 111 having critical titers or anti-Kell. A total of 70/111 (63%) infants had hemolytic anemia with 47/70 (67%) with a positive DAT. Anemia persisted longer than 1 month in 15/70 (21%) infants; 6/15 (40%) had an anti-D. Infants with anti-D were more likely to receive intrauterine and exchange transfusions (8/14 vs. 0/56), simple transfusions (6/14 vs. 8/56; p=0.008), IVIG (7/14 vs. 7/56; p= 0.005) and undergo readmission for anemia (5/14 vs. 5/51 p 0.03). Erythropoietin was given to 4 IUT recipients with reticulocytopenia at birth.  They had anemia resolution by 60 days of life.

Conclusions:

HDFN is severe in D antigen positive infants born to D- alloimmunized individuals, with anemia lasting up to 60 days. Use of erythrocyte stimulating agents may reduce duration of anemia in IUT recipients. Time-sensitive transition of care across multiple providers is essential for comprehensive management of HDFN in infants up to 3 months post-partum.